Locator for collars in well casings



A ril 13, 1965 M. a. CONRAD 3,177,941

LOGATOR FOR COLLARS IN WELL CA-SINGS Filed July 22, 1963 4 Sheets-Sheet 1 I N V EN TOR. Menu .5. (m/e40 Ar roe/V15 vs.

April 13, 1965 M. B. CONRAD LOGATOR FOR COLLARS IN WELL CASINGS 4 Sheets-Sheet 2 Filed July 22, 1963 V INVENTOR. Menu 6. 6 014/240 Arm/QM: vs.

April 13, 1965 M. B. CONRAD LOCATOR FOR COLLARS IN WELL CASINGS 4 Sheets-Sheet 3 Filed July 22, 1963 INVENTOR. Merl/v B, (on/P40 fwwf Arme/vzys.

April 13, 1965 M. B. CONRAD LOCA'I'OR FOR COLLARS IR WELL CASINGS 4 Sheets-Sheet 4 Filed July 22, 1963 Mmer/N B. Cave/70 INVENTOR.

flrraeusys.

United States Patent 3,177,941 LOCATOR FOR COLLARS 1N WELL CASINGS Martin B. Conrad, Downey, Calif., assignor, by mesne assignments, to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed July 22, 1963, Ser. No. 297,995 Claims. (Cl. 166-64) This invention relates to oil well casing; and more particularly to means for locating casing collars after the casing is in place.

Well casing comprises lengths of pipe, externally threaded at both ends and joined together by collars threadedly engaging these ends. The pipe lengths are not uniform; they may be as short at twenty feet or as long as forty feet. The pipe is sunk into the well, a

length at a time.

By appropriate well-known means, the depth of significant oil-bearing strata encountered during drilling operations is determined; after the casing is in place, the well is logged by appropriate apparatus, so that the depths at which the collars are located with respect to these strata are determined. Now when it is desired, for example, to perforate the well casing at a definite level corresponding to a significant stratum, the perforator apparatus should be quite accurately positioned in the well, especially if the stratum is quite shallow.

It is one of the objects of this invention to make it possible to obtain such accurate positioning, utilizing the logged depths of the collars as reference points. For example, if the desired depth at which a casing perforator is to be used lies between two collars identified on the well log, then in accordance with this invention, a dog or the like lowered into the well can be caused to engage either one or the other of the opposed edges of adjacent pipe lengths at one of the collars neighboring the desired location. Such engagement of the dog restrains movement of the dog in one or the other direction along the well. This restraint is translated into a definite sig- .nal, such as a greatly increased resistance to raising or lowering of the collar locator. This signal may be perceived, for example, by dip or jump of an indicator needle of a conventional strain gauge or other weight indicating device attached to the hoisting apparatus.

In prior application, filed jointly in the names of Martin B. Conrad and John B. McElheny on August 15, 1958, under Serial No. 755,253, now US. Patent No. 3,061,010, collar locators capable of performing these functions are described and claimed. It is another object of this invention 'to simplify the structure, as well as the mode of operation of such devices.

This application is a continuation-in-part of my prior application Serial No. 787,164 filed January 16, 1959 and entitled Locator For Collars In Well Casings, now

abandoned.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several embodiments of the invention. For this purpose, there are shown a few forms in the drawings accompanying and forming part of the present specification. These forms will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is an elevation of apparatus incorporating the invention, shown as disposed in well casing illustrated in longitudinal section, parts of the device being broken away in order to reduce the overall length of 3,177,941 Patented Apr. 13, 1965 the figure; the collar locator being shown as disposed intermediate two pipe collars or couplings;

FIG. 2 is a view similar to FIG. 1, on an enlarged scale, some of the parts being shown in section and indicating the collar locator in sensing contact with a collar;

FIG. 3 is a sectional view taken along a plane corresponding to line 3-3 of FIG. 1;

FIG. 4 is a view, similar to FIG. 1, of a modified form of the invention;

FIG. 5 is a longitudinal sectional view, illustrating the modification of FIG. 4 in sensing contact with a collar;

FIGS. 6 and 7 are sectional views, taken respectively along planes corresponding to lines 66 and 7-7 of FIG. 4; a

FIG. 8 is a view similar to FIG. 1, illustrating a phase in the operation of the sensing device of the modification shown in FIG. 4;

FIG. 9 is a sectional view taken along a plane corresponding to line 99 of FIG. 8;

FIG. 10 is a fragmentary enlarged sectional view taken along a plane corresponding to line 1010 of FIG. 4;

FIG. 11 is an exploded view of the mounting for one of the sensing devices; and

FIG. 12 is a schematic view illustrating the hoisting apparatus for the drill string and a device for indicating the weight of the drill string.

In FIGS. 1, 2 and 3, well casing 1 is shown as formed of pipe lengths 1a joined by a series, of collars or conplings 2. These couplings or collars are threaded on adjacent pipe lengths 1a, the end surfaces 3 of the pipe lengths being spaced apart. These ends form shoulders against which a sensing member may abut.

A string 4 of tubing may be provided for carrying the collar locator and disposed longitudinally of the well casing 1. Cooperating with hoisting apparatus 50 for the string 4 (FIG. 12) is a conventional strain gauge or other device 51 for indicating the weight of the string 4. The gauge is shown as having an indicator 52. Suitable measuring devices (not shown) indicate the longitudinal position of the support 5 in the well.

Interposed in the string 4 is a support member 5 (FIG. 1) joined to the tubing 4 by the aid of end threads 6. The support member 5 has a reduced concentric intermediate portion 7. Longitudinally disposed on diametrically opposite sides on the reduced portion 7 are lugs 8 and 9. It also has an intermediate lug or boss 10. The lugs 8 and 9 both provide flat coplanar surfaces, such as 11 and 12, directed toward the left, as viewed in FIG. 3.

A pair of resilient elements in the form of rubber blocks 13 and 14 are respectively confined between the lugs 8 and 10 and between the lugs 9 and 10. These resiliently yielding elements are held in place by a retainer 15 held against the boss 10 by the aid of a number of machine screws 16. These machine screws thread into the boss 10 and their heads are disposed in counterbores to the apertures through which the threaded shanks of screws 16 pass. Furthermore, the retainer 15 has a central raised portion 17 capable of slidably contacting the interior surface of well casing 1.

An arcuate sensing member 18 has noncircular ends 19 respectively accommodated in appropriate sockets in the members 13 and 14. These ends may be square. The outer surface of this sensing member 18 is purposely made curved as indicated at 18a so that in the position of FIG. 1, the sensing member may move smoothly either upwardly or downwardly with respect to the well casing 1 without material restraint.

Due to the floating support of the ends 19 in the rubber blocks 13 and 14, an angular movement of the sensing 3. member 18 -is permitted. Furthermore, the pivot of angular movement of the sensing member 18 may be laterally displaced from that shown in FIG. 1, since the blocks 13 and 14 are conformable.

This is of importance when the sensing member .18 in the course of .its upward movement in the well casing 1 engages the-lower end of a pipe section. Such a position is 'indicated-inFIG. 2. In this position, the member 18 lies obliquely upward transverse to the direction of longitudinal movement. Further upward movement is strongly resisted and the observer at the topof the well then is apprised of the engagement of a collar- 2 with the sensing member 18, .as by .noting a jump of the indicator 52 (FIG. 12). Further upward movementfrom the position of FIG. 2 causes the resiliently yielding blocks 13 and 14 to be-compressed between ends 19 and the retain- .ing member 15. This compressive strain on the rubber blocks ,13 and 14 continues to increase until the sensing member 18 assumes a phantom-line position of FIG. 1, beyond which the resisting or compressive force is materially reduced, at which point the indicator 52 dips. In this phantom-line position, the direction of obliquity of the member 18 is.changed. The maximum compression of the rubber block 13 occurs'when there is a change from one direction of obliquity to another. The sensing member is designed to produce a signal capable of being detected by the indicating device 51. The added restraint may be of the order of one hundred pounds.

In the :process of moving the support member upwardly from the-position of FIG. 2, there is an angular movement of the sensing member 18, indicated by the full-line position and the phantom full-line position of the sensing member 18in FIG. 1. This angle is usually .quite limited, preferably not greater than 90. The sockets provided for the ends 19 of sensing member. 18 are so oriented as to assume a position normal to the casing 1 and-toathe longitudinal movement of the support member 5 when no stress is placed upon the sensing member 18. Accordingly, in either of the two positions of the sensingmember 18 illustratedin FIG. 1, there is a slight .torsional strain imposed upon the sockets in which the. ends-19 are disposed.

An important advantage attained by this construction is the reversiblemovemcnt of the sensing member 18 between the full-line and dotted-line position; and in either'position, the string of tubing 4 can be moved either section. However, an upward movement results in ultimately moving the sensing member 18 to the engaging position of FIG. 2. In this position, the sensing member 18 engages the end of a pipe section and also the interior surface of .collar 2, and is restrained from upward movementtherein until indeed the sensing member is urged to the phantom line position of FIG. 1.

After upwardzmovement of-the support member 5 is efiected to urge the sensing-member 18to this phantom l1nepos1tion,-downward longitudinal movement of the tubing 4 will ultimately cause the sensing member 18 atesection 22 providing a mounting for the sensingmember 23.

-As shown most clearly in FIG. 11, the mounting member 22 is provided with a central arcuate slot 24 intersected by a transverse slot 25. A cover member 26 has upper and lower flanges 27 and 28 extending over the upper andlower edges of the mounting member 22.

- pressive force on the ring.

4 It is held in place by screws 29. The outer surface of the cover member 26 is cylindrical to conformv to the interior surface of the well casing 1 and to slide thereover without material interference.

The sensing member 23 in this instance is a resilient ring entirely encompassing the support member 20 and extending through the slot 24. Thering 23 may be either elliptical or circular so long as it may maintain clearance with casing 1 except at the top of the .arch, corresponding to a tangential sliding contact-point between the ring and casing 1. This resilient ring is deformable or compressible-when it is in contact with an edge 3, and a collar 2 and tubing 4 is moved upwardly from the position of FIG. 5. Furthermore, the cross section of the ring 23 is such that the tubing 4 can be moved longitudinally upwardly or downwardly without any danger that the. ring 623 will be restrained against either direction of movement between collars.

The ring 23 is urgedtoward a position normal to the casing 1, by the aid of afiat spring 30 located in the transverse slot '25. Furthermore, a rubber layer 31 is provided within the ring 23 and fitting "the inner contour thereof. This rubber layer is firmly adhered by appropriate means to the ring 23. Thus, in the event that the ring v23 should break, the rubber ring 31 will maintain the'broken parts together so as not to permit these broken parts to drop into the well. I

In FIG. 4, the ring23 may be moved either upwardly or downwardly in the well. If it is moved upwardly, it finally assumes a position such as shown in FIG. 5. Such further upward movement will be strongly resisted by the compressive stresses imposed upon the ring 23. Ultimately the ring 23 assumes the position of' FIG. 8 in which the arch of the ring hasbeen flattenedvby a com- Further upward movement of thetubing 4 and the supportmember 20 will release the ring and cause it to assume a position slanting downwardly in the well casing 1.

In all other respects, the mode of operation of this form of the invention is substantially identical with that disclosed in FIGS. 1, 2 and 3.

The inventor claims:

1. Ina locator .for .collarsjoining tubular lengths of pipe: a support member adapted to be moved'longitudinally within'the lengths; and a single sensing structure .carriedby the support member comprising; a first element extending obliquely with respect to the longitudinal direction ofmotion of the support member, said elementbeing adapted to contact .the .edge of a collar thesupport member is moved in one direction and the first element is in contact with a collar; .one of said elements being resilient and yielding against angular .movement of the first element, due to continued movement of the support member after the first element contacts said edge, the, yielding action of the resilient element being sufficient to cause the first element to pass through a positionwhere it is normal to the direction of movement of the support member, and into a position wheretheresilient force is relieved, the said one of said elements being designed to impose a significant and de-- tectible reactive force upon said support member when said first element passes from said one oblique position to another;.and means for detecting said reactive force.

2. The combination as set forth in claim 1, in which the resiliently yielding .element is the second element.

3. The combination asset forth inclaim 1, in which the resiliently yielding element is a rubber block, the pivotal mounting being thereby floating, said block being compressedwhile the firstelement moves to said normal position, and acting after the normal position is passedto reverse the angular position of the first element.

4. The combinationas set forth in claim 1, in which the first element is arcuate to form an arch, the apex of the arch contacting the interior surfaces of the pipe lengths and collars as the support member moves longitudinally in the pipe lengths, and riding over the ends of the pipe length for one direction of movement of the support member, and the end of a pipe length serving to restrict movement of the first element when the support member moves in the other direction.

5. The combination as set forth in claim 1, in which the first element is arcuate to form an arch, the apex of the arch contacting the interior surfaces of the pipe lengths and collars as the support member moves longitudinally in the pipe lengths, and riding over the ends of the pipe length for one direction of movement of the support member, and the end of a pipe length serving to restrict movement of the first element when the support member moves in the other direction; and the resiliently yielding member is a rubber block in which the ends of the first element are pivotally mounted.

6. In a locator for collars joining tubular lengths of pipe: a support member adapted to be moved longitudinally within the lengths; and a sensing structure carried by the support member, comprising: a resilient arched element extending obliquely with respect to the longitudinal direction of motion of the support member; said arched element being adapted to contact a collar between pipe lengths; and means for mounting said arched element on the support member in such manner as to cause an angular movement of the arched element when the support member is moved in one direction and the arched element is in contact with a collar, so as to depress the arch as the arch passes to a position normal to the direction of movement of the support member, and to relieve the arch when the arched element passes beyond said normal direction.

7. The combination as set forth in clahn 6, in which the arched element is a complete ring encompassing the support member, and having such cross-section as to.

cause the ring to slide with respect to the pipe lengths for either direction of movement of the support member, except when the ring is restrained by the end of a pipe length.

8. The combination as set forth in claim 6, in which the mounting means includes a member permanently joined to the support member and having an arcuate recess therein for the accommodation of the arcuate member, and a cover for the recess.

9. The combination as set forth in claim 6, in which the arched element is a complete ring encompassing the support member, and having such cross-section as to cause the ring to slide with respect to the pipe lengths for either direction of movement of the support member, except when the ring is restrained by the end of a pipe length; and in which the mounting means includes a member permanently joined to the support member and having an arcuate recess through which the ring passes, a cover for the recess, and a spring member extending transversely of the recess, for urging the ring toward the cover.

10. The combination as set forth in claim 6, in which the arched element is a complete ring encompassing the support member, and having such cross-section as to cause the ring to slide with respect to the pipe lengths for either direction of movement of the support member, except when the ring is restrained by the end of a pipe length; and with the addition of a rubber ring covering at least a part of the resilient ring and adhered thereto.

11. In a locator for collars joining tubular lengths of pipe: a support member adapted to be moved longitudinally within the lengths; and a sensing structure including a contacting member carried by the support member so as to lie obliquely to the longitudinal move-.

ment, and having a free end projected outwardly toward the interior surface of the tubular lengths; said free end being adapted to engage the end surface of a pipe length as the support member moves longitudinally of the lengths, a pivotal mounting for the contacting member; said mounting serving to impose a compressive stress on said contacting member upon continued movement to reduce the obliquity; a compressible resilient element in said sensing structure to sustain said stress; said stress being relieved when the direction of obliquity changes, the yielding action of the resilient element being sufl'icient to permit the change in direction, the said resilient element being designed to imposed a significant and detectible reactive force upon said support member when said contacting member passes from one oblique position to pipe, adjacent lengths having spaced end surfaces; a support adapted to be moved longitudinally within the lengths; a sensing member normally extending obliquely to the longitudinal directionof motion of the support; said sensing member having a free'portion for engaging the end edge surface of a length of pipe upon longitudinal movement of the support to stop further longitudinal movement of the free portion; a member pivotally mounting the sensing member on the support for angular movement of said sensing member relative to the support, the angular movement being on an axis transverse to the longitudinal movement; one of said members being resilient and yielding against angular movement of the sensing member upon continued longitudinal movement of the support after engagement of the free portion with a pipe end edge; the yielding action of the resilient member being suflicient to cause the sensing member to pass through a position where it is normal to the direction of movement of the support, and into a position where the resilient force is relieved, the said one of said members being designed to impose a significant and detectible reactive force upon said support member when said sensing member moves from said one oblique position past said normal position to the other oblique position; and means for detecting said reactive force.

13. The combination as set forth in claim 12, in which the resilient member is compressible.

14. The combination as set forth in claim 12, in which the resilient member is the mounting member, and is capable of yielding ultimately to'permit the sensing member to pass through and beyond a maximum yielding position.

15. The combination as set forth in claim 12, in which the resilient member is the sensing member formed as a substantially complete loop and angularly movable aboutv an axis adjacent the periphery of the loop.

References Cited by the Examiner UNITED STATES PATENTS 2,224,412 12/40 Smith 166-4 2,885,007 5/59 Hotter 166-214 2,999,542 9/61 Myers 166-214 BENJAMTN HERSH, Primary Examiner. CHARLES E. OCONNELL, Examiner. 

6. IN A LOCATOR FOR COLLARS JOINING TUBULAR LENGTHS OF PIPE: A SUPPORT MEMBER ADAPTED TO BE MOVED LONGITUDINALLY WITHIN THE LENGHTS; AND A SENSING STRUCTURE CARRIED BY THE SUPPORT MEMBER, COMPRISING: A RESILIENT ARCHED ELEMENT EXTENDING OBLIQUENLY WITH RESPECT TO THE LONGITUDINAL DIRECTION OF MOTION OF THE SUPPORT MEMBERS; SAID ARCHED ELEMENT BEING ADAPTED TO CONTACT A COLLAR BETWEEN PIPE LENGHTS; AND MEANS FOR MOUNTING SAID ARCHED ELEMENT ON THE SUPPORT MEMBER IN SUCH MANNER AS TO CAUSE AN ANGULAR MOVEMENT OF THE ARCHED ELEMENT WHEN THE SUPPORT MEMBER IS MOVED IN ONE DIRECTION AND THE ARCHED ELEMENT IS IN CONTACT WITH A COLLAR, SO AS TO DEPRESS THE ARCH AS THE ARCH PASSES TO A POSITION NORMAL TO THE DIRECTION OF MOVEMENT OF THE SUPPORT MEMBER, AND TO 